摘要:

Plant tissue analysis can be utilized by golf course superintendents to monitor a fertility program and to determine the nutrient status of turfgrass. The objectives of this study were to compare washed and unwashed plant tissue samples and to assess the nutrient status of golf course putting greens of creeping bentgrass (Agrostis palustrisHuds. ‘Penncross'). Turfgrass clippings were collected monthly from 18 putting greens from January through June, 1993. A portion of each sample was washed with deionized water, while the remainder of the sample was not washed. Plant tissue was dried at 70°C for 72 hr at which time dry weights were determined. Samples of both washed and unwashed plant tissue were analyzed for both macro‐ and micronutrient composition. There were differences between the washed and unwashed tissue samples for macro‐ and micronutrients for certain months. The range in concentration for the unwashed samples for a given nutrient in a given month was generally greater than the range in values for the washed sample of the given nutrient. This indicates the possibility of soil contamination from cultural practices and/or course player use for the unwashed samples. Nutrient analyses of the washed plant tissue samples gave a more consistent and reliable status of the nutrient content of creeping bentgrass on the greens.

ISSN:0010-3624    

DOI:10.1080/00103629409369092

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Lime application to acid soils usually increases N mineralization but little is known about how it affects the N determined by methods that assess organic N availability. One incubation and three chemical methods were compared in twenty samples of unlimed or limed soils in a pot experiment with maize (Zea mays,L). The N availability methods included the NH4+‐N released from soils by: a) anaerobic incubation for 7 days at 40°C; b) 2 mol/L KC1 at 100°C for 4 hours and distilled with MgO (hot KCl); c) this same procedure but distilled with 5 mol/L NaOH (hot KCl‐NaOH); and d) 30% v/v H2O2and MnO2. In addition, inorganic N, total N and organic C were also determined in the soil samples. Readily available inorganic N presented the highest correlation coefficient with N uptake by maize but anaerobic incubation, hot KCl, hot KCl‐NaOH, and total N were also good predictors of soil N availability. The H2O2/MnO2procedure and organic C produced inconsistent results. The amounts of N extracted by the methods tested were little affected by lime application. Multiple regression analysis showed that, among the methods that assess mineralizable organic N, the hot KCl methods accounted for most of the variation in N uptake by maize.

ISSN:0010-3624    

DOI:10.1080/00103629409369093

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

After the introduction of new soil test methods in the state of Sao Paulo in 1983, a sample exchange program was organized with the objective of encouraging uniform use of the methods and to improve the analytical quality of the results. The program started in 1984 with the laboratories that adopted the new methods and has increased almost linearly during the last years, attaining 50 laboratories from 6 states in 1992. Statistical criteria were adopted for the rejection of discrepant results. A system for ranking laboratories was developed based on error estimation due to inaccuracy and imprecision. Analytical difficulties and most common errors have been discussed during annual meetings of the program. All laboratories involved use the same methods and errors due to inaccuracy and imprecision were, in 1992, reduced respectively to 36% and 44% of the values of 1986. The program contributed to increase credibility of soil analysis in Sao Paulo state.

ISSN:0010-3624    

DOI:10.1080/00103629409369094

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

High Performance Ion Chromatography (HPIC) methods for measuring sulfate in 20 mMphosphate extracts of soil need to cope with low sulfate (down to 0.1 ppm S) in up to 5000 times the molar concentration of phosphate and potassium or calcium, a diversity of solutes including organic compounds, and colloidal particles.

ISSN:0010-3624    

DOI:10.1080/00103629409369095

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Although water retention and movement in soils determine both the need for irrigation and the loss of nitrogen (N) from agricultural systems, soil physical tests are generally too time‐consuming for routine analysis by soil testing laboratories. We evaluated the potential of the Moisture Equivalent (ME) method as described by Bouyoucos for routine soil physical measurement. The method consists of saturating a sieved soil sample in a Buchner funnel, vacuum filtering the sample for 15 min while covered, then determining the gravimetric water content. On 72 soil samples run in triplicate, ME results were highly repeatable (CV values generally less than3%).In addition, ME results were linearly correlated to clay and organic matter contents (R2= 0.85) and to 33 kPa moisture content (R2= 0.85). We conclude that the ME method is sufficiently convenient to run routinely in a soil testing laboratory, and sufficiently dependable to improve precision in irrigation and N management. Interpretive criteria for applying ME results will require verification through field calibration studies.

ISSN:0010-3624    

DOI:10.1080/00103629409369096

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Using hand‐held electrodes to analyze the nitrate‐nitrogen (NO3‐N) and potassium (K+) concentration in expressed plant sap to assess the supply of these nutrients has potential for improving nutrient management in greenhouse production of vegetable transplants. There is limited information available from research and experience by which to interpret the results for field‐grown crops, but virtually none for the pre‐transplant seedling stage. In order to derive diagnostic criteria for seedling tomatoes, I conducted greenhouse experiments in which the concentrations and application intervals of N and K fertilizers were varied. Results indicate that NO3‐N concentrations as low as 500 μg/mL in expressed stem sap may be sufficient to prevent seedling growth limitations. Results do not permit establishment of diagnostic criteria for K+in expressed stem sap. Frequency of fertilizer application appears to be more important than concentration of nutrients in fertilizer solutions in maintaining NO3‐N concentrations in stem sap and preventing growth limitation in transplant production.

ISSN:0010-3624    

DOI:10.1080/00103629409369097

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Spatial and statistical variability in soil characteristics must be addressed in using soil testing to guide precision nutrient management. This paper provides a case study comparing strategies using technology currently available and economically viable for farmers or their advisors to use for this purpose. The first strategy is to divide a large area into smaller subunits for sampling, then to map results by assigning the soil test value for each sample to the entire subunit, resulting in a mosaic of soil test values across the entire sampling area. An alternative approach involves collecting soil samples from known locations using global positioning system (GPS) technology, then mapping the spatial distribution of soil test results. The final strategy is to use the cumulative distribution function (CDF) to find the percentage of samples with soil test values at or below certain levels irrespective of their location. Based on 72 soil samples from a highly variable 40 ha research site, we found that inaccuracy of GPS may limit its application. Maps communicate soil test results readily, but may be difficult to apply in fertilizer management. The CDF approach provides useful information, but interpreting and applying the information may be difficult. Any of these methods of assessing soil test variability will require analysis of far more samples than composite sampling, and the value of the added information must justify increased analytical costs.

ISSN:0010-3624    

DOI:10.1080/00103629409369098

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The hot water extractable boron (HWB) soil‐test procedure does not lend itself to rapid routine analysis. This study was conducted to evaluate boron (B) chelates in extracting soil B in comparison to the HWB soil‐test procedure. The following B chelates were examined as soil B extractants: mannitol, salicylic acid, 2‐hydroxyisobutyric acid, and sorbitol. Soil B chelate extractants were prepared in a buffered solution that contained IN ammonium acetate and 0.1M triethanolamine. For each respective chelate, chelate concentrations were evaluated at 0.05, 0.2, and 0.5M at a soil:extract ratio of 1:4, extract pH of 7.3, and a shake time of 15 minutes for extracting soil B. For only the sorbitol B extractant (0.2M), various soihextract ratios (1:2, 1:4, 1:6, and 1:10), extract pH (5.0, 7.3, and 8.8), and shake times (15, 30, 60, and 120 min) were examined. All soil B determinations were by ICP. Maximum amounts of B were extracted at a chelate concentration of 0.2M for all four chelates evaluated. Maximum amounts of B were extracted at pH 5.0, 1:6 soiL:extract ratio and a shake time of 120 min. Based on laboratory efficiency and instrument detection limits, a chelate concentration of 0.2M, 1:4 soil extract ratio, pH 7.3, with a shake time of 15 minutes was selected for standard operating procedures. Soil extractants were ranked in terms of amount of soil B extracted as follows: HWB>mannitol=sorbitol>salicylic acid>2‐hydroxyisobutyric acid. Quadratic regression equations explained 84 to 88% of the HWB variability when mannitol, salicylic acid, or sorbitol were used as the independent variable. Stepwise regression equations were developed that explained 90 to 92% of the HWB variability when soil pH in addition to chelate extractable B was entered into the equation. Based on chelate expense and ability to extract soil B, sorbitol would be suggested as a replacement for the HWB soil test procedure in determining available soil B.

ISSN:0010-3624    

DOI:10.1080/00103629409369099

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Previous research shows that the diagnosis and recommendation integrated system (DRIS) and modified‐DRIS (M‐DRIS) have inherently biased data base means and CV's that affect the accuracy of nutrient diagnoses. Our objective was to remove these biases and determine their effect on phosphorus (P) and potassium (K) diagnoses for soybean (Glycine maxL.). Four sets of soybean M‐DRIS nutrient norms (linear, L; log‐transformed, LT; corrected anti‐log, CAL; and corrected anti‐log population, CALP) were derived for use in evaluating P and K deficiencies and sufficiencies. The four data bases differed in that: (i) the L, LT, and CAL norms were developed from 639 soybean leaf samples yielding in excess of 3500 kg/ha, while those for CALP were calculated from 3898 samples from all available yield levels, (ii) L norms were calculated from non‐log‐transformed nutrient data, while LT, CAL, and CALP norms were calculated from log‐transformed data, and (iii) CAL and CALP concentration means were developed by taking the anti‐log of their LT concentration means and CAL and CALP ratio means were calculated directly from their anti‐log concentration means. Results show that biased means and CV's for L produced inflated function and index values, which resulted in an over‐emphasis of P and K deficiencies compared with CAL. While log‐transforming data used to derive nutrient norms resulted in removal of mathematical biases from the means and CV's, use of LT norms also over‐ emphasized P and K deficiencies compared with CAL. Phosphorus and K diagnoses by CAL and CALP did not differ, indicating that leaf analyses from all appropriate plants may be used to derive corrected anti‐log norms without regard to yield level.

ISSN:0010-3624    

DOI:10.1080/00103629409369100

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

There is currently a great deal of concern about the movement of nutrients from agricultural land to surface and ground water. This concern centers on nitrogen (N) and phosphorus (P). These two nutrients greatly stimulate algal growth, ultimately causing a depletion of oxygen which adversely affects aquatic vegetation, and higher marine life. The Virginia Agronomic Land Use Evaluation System (VALUES) restructures and reorients soil test fertilizer recommendations to include the best currently available scientific technology on water quality oriented nutrient management. A data base has been developed for the major soil types in the mid‐Atlantic United States region with fertilizer rates to apply directly related to the particular soil being cultivated. This data base contains corn, soybean, and wheat yield information for over 550 soils. VALUES is being installed in the Virginia Tech Soil Testing Laboratory computer system for preparation of water quality oriented crop fertilizer recommendations.

ISSN:0010-3624    

DOI:10.1080/00103629409369101

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor